I'm really curious because on this link provided by stopcrazypp. http://www.nrel.gov/vehiclesandfuels/energystorage/pdfs/45048.pdf It may be possible to substantially increase battery life in warmer climates if the owner also has shorter trips (~35%-50% dod) and can modify the set-point to keep the batteries cooler. I imagine Tesla picked whatever temperature they use because the average cost of electricity may make lower target temps infeasible for anyone on the grid. So for most people the extra cost of cooling may be less than the extra cost of a new pack. However, those of us with solar panels have a different economic picture and may want to trade a little more electricity (install additional PV panels) for longer battery life.